Document Detail


Flow dependence of measures of aortic stenosis severity during exercise.
MedLine Citation:
PMID:  7930259     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
OBJECTIVES: This study was designed to investigate the effect of altering transvalvular volume flow rate on indexes of aortic stenosis severity (valve area, valve resistance, percent left ventricular stroke work loss) derived by using Doppler echocardiography. BACKGROUND: Assessment of hemodynamic severity in aortic stenosis has been limited by the absence of an index that is independent of transvalvular flow rate. The traditional measurement of valve area by the Gorlin equation has been shown to vary with alterations in transvalvular flow. Recently, valve resistance and percent stroke work loss have been proposed as indexes that are relatively independent of flow. Although typically derived with invasive measurements, valve resistance and percent stroke work loss (in addition to continuity equation valve area) can be determined noninvasively with Doppler echocardiography. METHODS: We performed 110 symptom-limited exercise studies in 66 asymptomatic patients with valvular aortic stenosis. Continuity equation valve area, valve resistance (the ratio between mean transvalvular pressure gradient and mean flow rate) and the steady component of percent stroke work loss (the ratio between mean transvalvular pressure gradient and left ventricular systolic pressure) were assessed by Doppler echocardiography at rest and immediately after exercise. RESULTS: Mean transvalvular volume flow rate increased 24% (from [mean +/- SD] 319 +/- 80 to 400 +/- 140 ml/s, p < 0.0001); mean pressure gradient increased 36% (from 30 +/- 14 to 41 +/- 18 mm Hg, p < 0.0001); continuity equation aortic valve area increased 14% (from 1.38 +/- 0.50 to 1.58 +/- 0.69 cm2, p < 0.0001); valve resistance increased 13% (from 137 +/- 81 to 155 +/- 97 dynes.s.cm-5, p < 0.0001); and percent stroke work loss increased 17% (from 17.4 +/- 6.9% to 20.3 +/- 8.5%, p < 0.0001). The effects of flow on valve area, valve resistance and percent stroke work loss were independent of the presence of an aortic valve area < or = or > 1.0 cm2 or reduced transvalvular flow rate (rest cardiac output < 4.5 liters/min). CONCLUSIONS: In patients with asymptomatic aortic stenosis, Doppler echocardiographic measures of valve area, valve resistance and percent stroke work loss are flow dependent. Flow dependence is observed with valve area < or = or > 1.0 cm2 and in the presence of both normal and low transvalvular flow states. The potential effects of transvalvular flow should be considered when interpreting Doppler measures of aortic stenosis severity.
Authors:
I G Burwash; A S Pearlman; C D Kraft; C Miyake-Hull; N L Healy; C M Otto
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Publication Detail:
Type:  Clinical Trial; Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of the American College of Cardiology     Volume:  24     ISSN:  0735-1097     ISO Abbreviation:  J. Am. Coll. Cardiol.     Publication Date:  1994 Nov 
Date Detail:
Created Date:  1994-11-22     Completed Date:  1994-11-22     Revised Date:  2010-03-24    
Medline Journal Info:
Nlm Unique ID:  8301365     Medline TA:  J Am Coll Cardiol     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1342-50     Citation Subset:  AIM; IM    
Affiliation:
Department of Medicine, University of Washington, Seattle.
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MeSH Terms
Descriptor/Qualifier:
Adult
Aortic Valve / physiopathology
Aortic Valve Stenosis / physiopathology*,  ultrasonography*
Blood Flow Velocity / physiology
Cardiac Output / physiology
Coronary Circulation / physiology
Echocardiography, Doppler*
Electrocardiography
Exercise Test
Exercise Tolerance / physiology*
Humans
Ventricular Function, Left / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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